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SubjectRe: [RFC PATCH] arm64: topology: Map PPTT node offset to logic physical package id
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Hi Shunyong,

On 28/06/18 10:18, Shunyong Yang wrote:
> As PPTT spec doesn't define the physical package id,
> find_acpi_cpu_topology_package() will return offset of the node with
> Physical package field set when querying physical package id. So, it
> returns 162(0xA2) in following example.
>
> [0A2h 0162 1] Subtable Type : 00 [Processor Hierarchy
> Node]
> [0A3h 0163 1] Length : 1C
> [0A4h 0164 2] Reserved : 0000
> [0A6h 0166 4] Flags (decoded below) : 00000003
> Physical package : 1
> ACPI Processor ID valid : 1
> [0AAh 0170 4] Parent : 00000000
> [0AEh 0174 4] ACPI Processor ID : 00001000
> [0B2h 0178 4] Private Resource Number : 00000002
> [0B6h 0182 4] Private Resource : 0000006C
> [0BAh 0186 4] Private Resource : 00000084
>
> So, when "cat physical_package" in /sys/devices/system/cpu/cpu0/topology/,
> it will output 162(0xA2). And if some items are added before the node
> above, the output will change to other value.
>
> This patch maps the node offset to a logic package id. It maps the first
> node offset to 0, the second to 1, and so on.
>
> Then, it will not output a big value, such as 162 above. And it will
> not change when some nodes(Physical package not set) are added.
>
> And as long as the nodes with Physical package field set in PPTT keeps
> the real hardware order, the logic id can map to hardware package id to
> some extent.
>
> Hope to get feedback from you.

Thanks for the patch, but Andrew Jones has also posted a patch[1] which
I had a look but was not sure what is the best approach to fix it yet.
I will think about it and respond to that.

--
Regards,
Sudeep

[1] https://patchwork.kernel.org/patch/10482261

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